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I guess I'm confused. You're not contemplating putting an R134a fitting on a system that's still got R12 in it, are you?

A valve core tool is only a few dollars, once the system is empty you can unscrew it and install a new core. They're only a few dollars, also.
 

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The GRIM REAPER CHEATER
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Also having trouble with my a/c clutch but posted in a hurry and didn't take the time to look and see if there was another one running~sorry~ i took my truck to get the system recharged this morning and the clutch would not kick in so had to get it repaired and try and go back tomorrow to get it recharged. began chasing parts looking for a clutch dealer wanted $444.22 just for the part so that was out junkers wanted $100 for compressor they would not take the clutch off and i would have had to evacuate the system which i didn't want to do so long story short i took a flat blade screwdriver and moved the clutch out manually and restarted the truck and the clutch has been working fine though only staying cold for about 5 min. and then going warm again so i'm going to take a chance tomorrow and try and get it recharged again...Gene
Took my truck back again this morning and the clutch was working he put the gauges on and it didn't need any R134a the charge was up but then it started blowing warm air again so he condemmed the clutch and no matter what he did the clutch would not engage again so he put some wd40 in around the inside of the clutch shaft but that didn't help. left there and went to my mechanic and asked him to take or blow the wd40 out of there because i didn't think that would help and he used brake cleaner to clean it up but could not to get the clutch to engage so we left it at that so i came home wife wanted to go to daughters so i put 2 screw driver one on each side and moved the clutch out with mild force and it kicked in when we left but it started to run warm again about 5 minutes in so i guess i'll have to try and get a used compressor to get the clutch from and start again...Gene
 

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Discussion Starter #23
I guess I'm confused. You're not contemplating putting an R134a fitting on a system that's still got R12 in it, are you?

A valve core tool is only a few dollars, once the system is empty you can unscrew it and install a new core. They're only a few dollars, also.
Nope - the R12 is coming out first. Then, the adapters go on and HC-12a goes in. Will do that part myself, again. Fourth time. Going to buy the dyed stuff too, just in case this ever happens again and I want to find the leak fast. Would still rather get my hands on the non-HC blends, but that's probably not happening in Canada anytime soon. The HC's have become rather popular. Used to be I had to go looking for them, and only one store had them. Now, you can get it at Wal-Mart and Canadian Tire.
 

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How do i bypass the switch on a compressor to make sure the clutch on another compressor to make sure the clutch is working i have a chance at a clutch on another compressor but want to make sure the clutch is working.Thanks...Gene
 

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Nope - the R12 is coming out first. Then, the adapters go on and HC-12a goes in. Will do that part myself, again. Fourth time. Going to buy the dyed stuff too, just in case this ever happens again and I want to find the leak fast. Would still rather get my hands on the non-HC blends, but that's probably not happening in Canada anytime soon. The HC's have become rather popular. Used to be I had to go looking for them, and only one store had them. Now, you can get it at Wal-Mart and Canadian Tire.

Just remember, mineral oil used in R12 systems is not compatable with R134a. It will not be carried by R134a refrigerant.
If you can get by with HC-12a hydrocarbon refrigerant in your part of Canada, that would probably be your best bet. I'm not sure how well the 6C17 compressor would handle this because it is a variable displacement compressor and its output is based on a pressure/temperature curve.
I would check with your AC guy to see if these conversions have been successful. IIRC HC-12a performs similar to R12 so my gut feeling is that it will work OK.

ADDITIONAL: I just found this article regarding conversions of vehicles using variable displacement compressors.

http://www.imcool.com/articles/aircondition/max_cooling_dodge_minivan.htm


NOTE TO GENE:
Find your AC relay and jumper terminals # 30 & 87. That should force power to the clutch.
 

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Just remember, mineral oil used in R12 systems is not compatable with R134a. It will not be carried by R134a refrigerant.
If you can get by with HC-12a hydrocarbon refrigerant in your part of Canada, that would probably be your best bet. I'm not sure how well the 6C17 compressor would handle this because it is a variable displacement compressor and its output is based on a pressure/temperature curve.
I would check with your AC guy to see if these conversions have been successful. IIRC HC-12a performs similar to R12 so my gut feeling is that it will work OK.

ADDITIONAL: I just found this article regarding conversions of vehicles using variable displacement compressors.

http://www.imcool.com/articles/aircondition/max_cooling_dodge_minivan.htm


NOTE TO GENE:
Find your AC relay and jumper terminals # 30 & 87. That should force power to the clutch.
Thanks john just 2 wires coming from the power to the clutch i'm assuming that the black is the ground forget the other color it's striped and hoping this is the power...Gene
 

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Discussion Starter #27
Just remember, mineral oil used in R12 systems is not compatable with R134a. It will not be carried by R134a refrigerant.
If you can get by with HC-12a hydrocarbon refrigerant in your part of Canada, that would probably be your best bet. I'm not sure how well the 6C17 compressor would handle this because it is a variable displacement compressor and its output is based on a pressure/temperature curve.
I would check with your AC guy to see if these conversions have been successful. IIRC HC-12a performs similar to R12 so my gut feeling is that it will work OK.
Yeah, the oil thing is one of the big reasons I haven't driven any of the family vehicles across the border to do 134a retrofits. Just the thought of flushing and changing the oil gives me a headache. It's also the reason I would use one of the mineral oil compatible blends in a heartbeat over 134a.

Wasn't sure about the HC12a in the 6C17 either, but I also get the impression it'll probably work fine. I'll find out next week. Takes 11 ounces of it for this car... if that doesn't do it, time to figure something else out. Once the R12 is out of there, all it'll cost me is $40 at most to find out whether it works. I know it works with the C171, but of course that's not a variable displacement compressor. I'll keep a close eye on it while charging... if I hear any objectionable noises, or it doesn't cool properly, I'll kill the clutch power and see if I can figure something else out.

Didn't even think that the 6C17 would possibly have trouble with R134a or other non HC blends. If HC12a does work well in there, I might just leave it alone.

Converted my first 134a vehicle to HC12a last year. 2002 Caravan. Here I thought the stuff already worked well in older systems. It got so brutally cold in there you couldn't leave it on the coldest setting for long. Not sure offhand what compressor is in there, but it handled the stuff ok.
 

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Thanks john just 2 wires coming from the power to the clutch i'm assuming that the black is the ground forget the other color it's striped and hoping this is the power...Gene

Another way to force the clutch to engage would be to ground that black wire and connect battery to the other wire. I still prefer bypassing the relay. The terminal numbers are usually marked in fine print on the bottom of the relay case. Once you know which sockets correspond to terminals 30 & 87, you can make a short wire jumper to connect in those socket. The vehicle won't even need to be running (but the key may need to be in the run position) for you to engage the clutch. You should hear it snap closed when you put the jumper wire in.
 

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ADDITIONAL: I just found this article regarding conversions of vehicles using variable displacement compressors.

http://www.imcool.com/articles/aircondition/max_cooling_dodge_minivan.htm
Did some more Googling. Found one report of a 6C17 not performing well with HC-12a, but that was on one of the vans with a small condenser. My car doesn't have a small condenser. He was also overcharged.

I'll give it a try and see how it does. Common sense tells me that if the valve in the quoted article needs to go clockwise to cope with the higher R134a pressures, it has to go the other way for the hydrocarbons. I aim to be very careful with that valve, it I touch it at all.

Only thing I dread is getting to that valve in the first place. My car's engine bay is packed as it is. I may not be able to adjust it with the car running.

Edit - I think I've decided not to use just any HC-12a product, and go with Duracool. The blend is a bit different than most of the other HC-12a products up here (60/40 vs. 70/30), and it looks like it gets closer to R12 in performance than the others. My variable rate compressor may thank me for it. Sure, Redtek and its clones might have gotten colder and run at lower pressures in my New Yorkers, but this compressor isn't going to be expecting that. I may just get by without adjusting the valves if I go with Duracool instead.
 

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The oil is not an issue. I've converted several R12 systems to R134a. You flush the system, blow it out with compressed air, and add ester oil - takes about 6-7 oz total. Change the drier. Lube the gaskets with ester, bolt it up, pull a 1-hr vacuum, charge to 85% of the original weight of the R12. I've been running my 93 Daytona around Carlisle here, and it puts out 40F air. It was 90F here today, and I had the A/C on fan position 2 of 4 after the initial cooldown at position 3, and then position 1. It cools as well as the R12 ever did, in this car.
 

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Yeah - I think it's just the cost of everything needed more than anything else that bugs me about converting to 134a. Otherwise, it would be a piece of cake to do it, now that I know how much to adjust that main valve on the compressor. Of course, I could also swap compressors and lines to the 1993 R134a stuff, too.

Been researching the 6C17 all afternoon. Hope I haven't confused myself too much by now. My main weapons in charging it will be the gauge on the good charging hose I got in the US last year, and my electronic dual thermometer with the 6' test leads. I'll know it if I need to adjust that valve. If the vent temps try to go below freezing or don't go low enough despite a full charge, and/or I see low side pressure stay significantly over 28psi, that'll be a clue the valve needs a tweak. Someone can correct me if I'm wrong. I don't think I'll be able to adjust it with the car running though... I'll just have to be ready to remove the serpentine belt a bunch of times as needed. And won't that be a blast on this car... almost has to be done from underneath if you don't have a belt tool, which I don't..

I worry about the evaporator icing up, actually. I saw vent temps down to one degree Celcius while charging the New Yorkers with the hydrocarbons. The ATC system apparently has no cut out sensor for that - the manual system got one. Wonder if it deals with that possibility in some other way. I would think though that the system depends on the high and low pressure sensors, as well as the variable displacement stuff working properly. All the more reason to be real careful with the system while I'm charging it. If anything about it makes me nervous, I'll happily remove the clutch power.

I think I probably am overthinking this, though. Duracool insists their stuff works on variable displacement compressors. From what I understand, the biggest potential problem with the 6C17 is that it won't cool as well as R12, not that it will cool better and ice up the evaporator. I think I'd be ok if the vent temps were a little warmer than they used to be, as long as I knew the compressor was happy and not having to work as hard.

I'll get lots of pictures for posterity, I think. There's very little info about the 6C17 and alternative refrigerants on the net. I should at least document how this turns out.
 

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Got the system evacuated since my last post. Leaky valve core fell apart when it came out - there was not a lot of spring left in that spring.

The new R134a low side fitting is on. I may try to find the right high side fitting in town this morning. The full amount of Duracool needed was purchased yesterday for $26 Canadian at Princess Auto Saskatoon who, contrary to the website, had plenty of stock. Charging happens this afternoon regardless of whether or not I find one. It's a bit cool out there right now, so I need the sun to heat things up a bit yet. Show and tell to follow. Today promises to be humid and warm... perfect AC charging weather.

Went to the west side Walmart supercenter in town as well. They had no Duracool left at all. I'm glad Princess was well stocked.
 

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I just got it all charged up. Good news and bad news.

The good news is, Duracool does work with variable displacement compressors. The bad news is, it doesn't work that well with this one. The main valve does need adjusting before this is going to work optimally. I'm waiting on another day to do that - too tired to mess with the serpentine belt today. I may yet drill the hole in the bracket so I can adjust it on the fly. I'd like an even warmer day for that.

Refrigerant capacity on the hood sticker was given as 34 ounces, so I let it have the entire contents of both Duracool cans and then purged just a bit out. That adds up to a slight overcharge. Debating letting a bit more out, but I only bought the two cans. I'll adjust the valve first and see if that improves things.

Charging was done at 26 Celcius (80 degrees Fahrenheit). First can went almost all the way in without the car running... the compressor came on as soon as I fired up the AC.

Road tested the car afterwards. On the highway, it cools well but not as well as it should. Coldest vent temp recorded was 12 Celcius, or 53 Fahrenheit. Cool, but not cold. It has trouble cooling when sitting still, to the point it was hard to get a good fix on the low side pressures. At the end of it, I saw it fluctuate between 35-45psi or so, telling me the compressor is probably ok with the charge level but isn't quite dealing with the HC-12a properly. I should see it average slightly lower than that.

The other good news though, is that the compressor does like Duracool better than the R12/air mix that was in there. No shudders on the highway when I manually kicked the compressor on and off. Clutch is still making noise, but not nearly as much. I might still have to do something about that.

Now for the pics:



The old valve.



The patient is ready for the transfusion, doctor. I must say I love that charging hose. It retains pressure when it comes off the fitting and also when refrigerant cans are removed.



Ambient temperature reading.



My fancy redneck charging jig. The can is upside down because this stuff charges as a liquid.



Fan settings for charging the first can. Note that "lo" indicates that the ATC is locked into full manual mode with the blend door all the way cold. I upped the fan to full power for charging the second can.



Vent temps at the end of can 1. Compressor running, but system not cooling very well yet. It never got a lot better than this - stays around 16 degrees Celcius when stopped. Fans did come on, but not for very long. Don't recall what the high side pressure is supposed to be when they kick on, but it didn't get high enough to run the fans that often.



Pressure reading at the end of can 1. Wish I'd remembered to get a pic of it after can 2.

More to come when I get around to fiddling with the valve. I've left the compressor clutch plugged in, but am debating unplugging it until I can get to tweaking the valve. I hate to have the compressor not working optimally.
 

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I just got it all charged up. Good news and bad news.

The good news is, Duracool does work with variable displacement compressors. The bad news is, it doesn't work that well with this one. The main valve does need adjusting before this is going to work optimally. I'm waiting on another day to do that - too tired to mess with the serpentine belt today. I may yet drill the hole in the bracket so I can adjust it on the fly. I'd like an even warmer day for that.

Refrigerant capacity on the hood sticker was given as 34 ounces, so I let it have the entire contents of both Duracool cans and then purged just a bit out. That adds up to a slight overcharge. Debating letting a bit more out, but I only bought the two cans. I'll adjust the valve first and see if that improves things.

Charging was done at 26 Celcius (80 degrees Fahrenheit). First can went almost all the way in without the car running... the compressor came on as soon as I fired up the AC.

Road tested the car afterwards. On the highway, it cools well but not as well as it should. Coldest vent temp recorded was 12 Celcius, or 53 Fahrenheit. Cool, but not cold. It has trouble cooling when sitting still, to the point it was hard to get a good fix on the low side pressures. At the end of it, I saw it fluctuate between 35-45psi or so, telling me the compressor is probably ok with the charge level but isn't quite dealing with the HC-12a properly. I should see it average slightly lower than that.

The other good news though, is that the compressor does like Duracool better than the R12/air mix that was in there. No shudders on the highway when I manually kicked the compressor on and off. Clutch is still making noise, but not nearly as much. I might still have to do something about that.

Now for the pics:



The old valve.



The patient is ready for the transfusion, doctor. I must say I love that charging hose. It retains pressure when it comes off the fitting and also when refrigerant cans are removed.



Ambient temperature reading.




My fancy redneck charging jig. The can is upside down because this stuff charges as a liquid.



Fan settings for charging the first can. Note that "lo" indicates that the ATC is locked into full manual mode with the blend door all the way cold. I upped the fan to full power for charging the second can.



Vent temps at the end of can 1. Compressor running, but system not cooling very well yet. It never got a lot better than this - stays around 16 degrees Celcius when stopped. Fans did come on, but not for very long. Don't recall what the high side pressure is supposed to be when they kick on, but it didn't get high enough to run the fans that often.



Pressure reading at the end of can 1. Wish I'd remembered to get a pic of it after can 2.

More to come when I get around to fiddling with the valve. I've left the compressor clutch plugged in, but am debating unplugging it until I can get to tweaking the valve. I hate to have the compressor not working optimally.

Nice pictures and detailed report. Thanks for sharing that.
What doesn't seem right is your statement of the fans coming on, but not staying on. An AC system generally requires a condensor fan to stay on constantly except for a brief period of low pressure, usually when the compressor first kicks in.. Is there a pressure transducer on this vehicle that controls the fans? It is very critical to move heat away from the condensor in order to get an efficient operating system.
I'm also wondering if that is what caused the noise and possible compressor bogging you mentioned in your earlier posts. Do you recall seeing the fans run before?

EDIT: I just looked it up, and the fan should stay on anytime the high pressure is 160 psi or higher. Also, the manual states that the normal high pressure range is 140 to 240 PSI and at pressures of 180 or higher, the compressor is running at full output similar to a fixed displacement compressor.
 

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Yeah, the fans are controlled with a pressure transducer. I expected them to come on less frequently.

I couldn't help myself - just spent an hour fiddling with the valve. Sweet spot seems to be around 1/2 turn counter clockwise, though I have yet to try setting it closer than that. I was now able to get 12 degrees standing still, so I went out on the highway. 12 degrees again. I reckon that's good - parked performance is coming closer to highway. I tried 3/4 turn and a full turn CCW as well - both times that killed performance.

So, I purged a little Duracool. 11 degrees. Diagnosis? I think she's just overcharged... that's all. There might be a little more tweaking I can do to the valve to optimize things, but it almost feels like R12 in there now. Almost. I want to put that hose back on with an empty can on the end and see what the low side pressure is doing.

FWIW, accessing that valve from underneath wasn't happening for me. I had to unbolt the compressor and pull it forward each time, and that valve was not easy to turn. Burned my hands often on the exhaust manifold. Drilling is definitely the way to go, but that requires removal of the bracket and one still might have problems adjusting that valve.

Edit - I should also report that the ambient outside temp is up to 27C, 81F. So it is working a little bit better with more of a delta.
 

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One more update before shower time.

I put the hose back on. My readings: system off, engine off - 80psi. Compressor on, it came down to 50, then 40. It then hovered between 38-40 as the variable displacement thing worked. Speeding up the engine dropped pressure to around 28psi.

Purged a little more Duracool. System off reading came down to 70psi. Went for a drive - ten degrees. Ambient is up to 30 degrees C.

Making real progress. An extra ounce of Duracool makes a big difference in an overcharge situation, I am now learning.
 

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One more update before shower time.

I put the hose back on. My readings: system off, engine off - 80psi. Compressor on, it came down to 50, then 40. It then hovered between 38-40 as the variable displacement thing worked. Speeding up the engine dropped pressure to around 28psi.

Purged a little more Duracool. System off reading came down to 70psi. Went for a drive - ten degrees. Ambient is up to 30 degrees C.

Making real progress. An extra ounce of Duracool makes a big difference in an overcharge situation, I am now learning.

It looks like you are in spec per the manual. Your biggest risk now would probably be releasing more refrigerant and going too far with it. I think one of the reasons they got away from variable displacement compressors was because they were very sensitive to over or under charge conditions.
 

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Yeah... I'm not purging any more until I fiddle with the valve again. Duracool is cheap, but I don't want to be buying cans over and over until I stumble on the right charge level and valve setting. Not to mention releasing the oil along with it. It really does seem awfully picky about the charge level.

I just have this feeling the valve is still too far out and that the proper setting is more like 1/4 turn CCW, considering the pressures I'm seeing are right in line with Duracool's instructions. From here, it should just be a case of getting the valve setting right. I'd like to see vent temps reach down to five degrees yet, but it's already starting to cool better than it was before the leaky Schrader valve got discovered. I'm close, just not quite there yet.

Real glad I'm not using Redtek or the other 70/30 blends. Those run at even lower pressures. Don't want to think about how many adjustments of the valve they would have taken.
 

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Today's update - valve setting is 1/4 turn CCW. Negligible effect on vent temps - I think the sweet spot for the valve is between 1/4-1/2 turn CCW.

Outside temp as shown on the EVIC was 25 degrees Celcius. Lowest vent temp with blower on high was 10 degrees. Blower on half speed, 9 degrees.

So I let a little more gas out. 9 degrees with blower on full, 7 degrees on half speed. Noted that there are no bubbles in the sight glass... with HC-12a, that means a likely overcharge. Compressor is running noticeably quieter.

I'm going to leave the valve alone now, and try to fiddle with the charge some more. Will let the gas out in very brief spurts to avoid losing too much.

In hindsight, I think my major errors here were A - assuming the guy got the whole R12 charge out (I'm starting to think he didn't, but then again the old valve core did come out), B - paying more attention to the low side gauge than the thermometer, and C - not allowing the system enough time to assimilate new refrigerant before letting more in. As such, I went right past the stopping point. It was much easier with the New Yorkers... those cars, I just charged until it got freakishly cold at the vents. That idea didn't work on this compressor, because it wasn't set up correctly for Duracool. And watching the low side pressure alone doesn't work either, because of the variable displacement.

While charging, I saw vent temps stop at 13 degrees but thought the low side pressure was too low. I should have quit right there and road tested the car to see what the vent temps were doing on the highway, and then adjusted the valve as needed.
 

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Another way to force the clutch to engage would be to ground that black wire and connect battery to the other wire. I still prefer bypassing the relay. The terminal numbers are usually marked in fine print on the bottom of the relay case. Once you know which sockets correspond to terminals 30 & 87, you can make a short wire jumper to connect in those socket. The vehicle won't even need to be running (but the key may need to be in the run position) for you to engage the clutch. You should hear it snap closed when you put the jumper wire in.
Thanks john i'll keep this info till it stops raining and warm again...Gene
 
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